I'm sorry about the issue. That was certainly a scam; they just want your money, so do not provide them your money or credit card or bank information, etc. If something sounds to good to be true, then it is. There are a lot of fake facebook accounts online. In the future, please always ignore any message (or phone call) that you do not know or that you are not expecting.
Also, you can open the facebook message from that scammer, then click on the gear (wheel) icon at the top, then click on the option Report Spam or Abuse..., and continue.
; You can also click on the scammer's name to go to her facebook profile page, then there, click on the 3-dot icon near the top, then select the Block option and continue.
Do you have any further question and/or do you need anything else?
Please reply at the box below to continue. Thank you.